Different transmission arrangements are used today throughout a variety of different systems for wireless transmission of data.
Wireless data transmission procedures using for example transformers typically involve modulation or coding. Coding and/or modulation is typically introduced to enable transmission of data and/or to enable detection of transmitted data and/or to prevent saturation of the transformer core by the data, i.e. to prevent excessive voltages from being applied to the transformer. Normally, to prevent saturation of the transformer, a balance type code is used. An example of such a code is the Manchester code which always returns to zero after each clock cycle. The Manchester code has a mean voltage value of zero over time. Ethernet transformers typically use Manchester coding.
One area within which wireless communication is gaining interest is within the area of telemetry, i.e. communication of measurement data and/or other signals associated thereto.
A typical application that involves a non-contact interface is a system involving a rotating device, to which communication may not be achieved by wire. In systems involving a rotating device there is however often a need for measuring one or more characteristics associated with the rotating device, such as for example the torque experienced by the rotating device, the temperature of said rotating device, the mechanical wear/stress of said rotating device and/or the angular velocity of said rotating device. Said measured characteristics can for example be used for one or more of the following purposes: controlling/monitoring the means used for applying rotation to said rotating device, monitoring one or more characteristic of the rotating device in order to assure that control reference values are followed by the rotating device, and to assure that no tolerance values associated with the rotating device are exceeded.
In some applications, contact-less sensors, i.e. sensors distantly positioned from a measurement object such as said rotating device, can be used for measurement of characteristics of the rotating device. However, in some applications contact-less sensors are unsuitable due to their limited accuracy. For applications wherein contact-less sensors are unsuitable, contact sensors contacting the measurement object have to be used instead.
Known systems for measuring one or more characteristics of a rotating device using one or more contact sensor are typically reliant on a wireless telemetry arrangement in order to retrieve data from the one or more contact sensor since performing measurements on a rotating device using one or more contact sensor implicates the one or more contact sensors rotating together with the rotating device, which presents difficulties with attaching wires to said one or more sensor.
A slip ring arrangement is an example of a known arrangement for providing a wireless connection from a rotating sensor, such as a rotating torque sensor, to receiving electronics. The slip ring arrangement consists of a number of conductive rings that rotate with the sensor, and a number of brushes that contact said conductive rings, rendering possible the transmission of measurement data to the receiving electronics.
Another known approach for transmission of measurement data from a rotating sensor is the use of an RF (radio frequency) transmitter, such as a FM transmitter sending a frequency modulated signal, wherein said RF transmitter is coupled to the rotating sensor for wireless transmission of the data to receiving electronics.
Another known approach for transmission of measurement data from a rotating sensor is the use of a rotary transformer. The rotary transformer is a specialized transformer used to couple electrical signals between two parts which rotate in relation to each other. The rotary transformer is coupled to transmit power to the rotating sensor. An external instrument provides an excitation voltage to a strain gauge bridge via an excitation transformer. The sensor strain gauge bridge then drives a second rotary transformer coil so as to receive a measurement signal from the rotating sensor.
Yet another known approach for providing wireless transmission of measurement data from a rotating sensor, such as a torque sensor, is the use of an IR torque sensor. Similarly to the rotary transformer approach described above the IR torque sensor draws power through a rotary transformer coupling. The IR torque sensor differs from the above rotary transformer approach in that measurement data from the IR torque sensor is transmitted via infrared light to stationary receiving diodes of receiving electronics.
However, the transmission arrangements including telemetry systems for providing wireless signal transmission according to prior art tends to suffer from one or more of the following drawbacks: require complex circuit(s) and/or large sized circuit(s) configuration(s), high power consumption, difficult to maintain, costly to build, limited bandwidth for signal transmission, limited transmission capabilities, and prone to wear.
Accordingly, there is a need to present improvements in the art of wireless signal transmission.